When starting from 1861, one would have 7 HQs, 8 if Garibaldi is in. But units count would be lower, and the number of active fronts also would be lower.
In short, number of Union HQs is rather inadequate for serious operations, and more cannot even be built, because of long queue of guys in production. Maybe ~2 HQs could be thrown in, or limit increased, or both?
CSA have 11 HQs, and UK additional 3, so it is 14:7 (not mentioning very sad placement of 2 Union generals)